1. Field of the Invention
This invention relates to a cleanroom transport system, and more particularly to a transport system for a cleanroom where clean air is caused to flow from a ceiling toward a floor surface. The transport system includes a guide rail laid in the cleanroom for guiding a load carrying vehicle. The vehicle has a main body for running along the guide rail, a load supporting deck disposed over the main body, and connecting members interconnecting the main body and load supporting deck.
2. Description of the Related Art
As shown in FIG. 29, a conventional cleanroom transport system has a tubular guide rail 31 defining an upper opening, with a main body 32 of a vehicle disposed inside the guide rail 31. This construction is designed to prevent dust produced between the guide rail 31 and running wheels 33 attached to the main body 32 from scattering to the interior of the cleanroom. The dust produced is drawn to air cleaners through a duct 34 or the like.
A load supporting deck 35 is disposed over the main body 32 and connected thereto through connecting members 36. A pair of covers 37 are attached to upper edges of the guide rail 31 to cover an upper opening of the guide rail 31, leaving only a slot for receiving the connecting members 36. The vehicle is propelled by a linear motor including primary coils 38 arranged in lower positions of the guide rail 31, and a secondary conductor plate mounted in a lower position of the vehicle.
In the cleanroom where clean air is caused to flow from the ceiling toward the floor surface, it is desirable to minimize disturbance of air flows caused by objects in the cleanroom. For disturbed air flows would cause dust to float in the cleanroom, and delay discharge of dust through the floor surface.
However, in the prior construction noted above, the guide rail tends to disturb the air flows. The air flows may be less disturbed where the guide rail has a streamline configuration with respect to the air flows. However, for the intrinsic purpose of the guide rail, strength and dimensional precision are an important consideration to which priority must be given. For reasons of manufacture and installation also, it has been difficult to provide the guide rail with such a streamline configuration.